Dogfish M4 lactate dehydrogenase

FIGURE 10.18 A stereo image of a small portion of an electron density map from dogfish M4 lactate dehydrogenase showing the position of a bound sulfate ion, circa 1969. 

Fig. 2.41. Contacts in neighboring subunits in dogfish M4 lactate dehydrogenase (according to Holbrook et al, 1975).

Simulate these mutants for dogfish M4 lactate dehydrogeanse (6LDH.pdb). After energy minimization, superimpose the wild-type and mutant enzymes and construct their animated kinemage files including views for the complete molecular structures and close-ups of the L-lactate dehydrogenase active site as identified by the ProSite. 

Most NAD+- or NADP+- dependent dehydrogenases are dimers or trimers of 20- to 40-kDa subunits. Among them are some of the first enzymes for which complete structures were determined by X-ray diffraction methods. The structure of the 329-residue per subunit muscle (M4) isoenzyme of lactate dehydrogenases (see Chapter 11) from the dogfish was determined to 0.25 nm resolution by Rossmann and associates in 1971.2 1 More recently, structures have been determined for mammaliam muscle and heart type (H4) isoenzymes,5 for the testicular (C4) isoenzyme from the... 

The amino acid sequences of corresponding regions from dogfish M4 and Bacillus stearothermophilus lactate dehydrogenases are shown below ... 

Abad-Zapatero, C., J.P. Griffith, J.L. Sussman, and M.G. Rossmann (1987). Refined crystal structure of dogfish M4 apo-lactate dehydrogenase. J. Mol. Biol. 198 445 167. 

FIGURE 1.14 Seen here is the hk0 zone diffraction pattern from a crystal of M4 dogfish lactate dehydrogenase obtained using a precession camera. It is based on a tetragonal crystal system and, therefore, exhibits a fourfold axis of symmetry. The hole at center represents the point where the primary X-ray beam would strike the film (but is blocked by a circular beamstop). Note the very predictable positions of the diffraction intensities. All the intensities, or reflections, fall at regular intervals on an orthogonal net, or lattice. This lattice in diffraction space is called the reciprocal lattice. 

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